UK light heavyweight Buatsi made a winning yet unimpressive debut to life under recent management with a decision win over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a competitive ten-round contest at the Co-op Live Arena.
But the challenger had his moments, landing some telling clean blows in a match where the styles never quite clicked, with excessive holding disrupting the action.
The scoring judges scored it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi stated in the ring as he was faced boos from the audience.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to claim a 20th career victory.
Some ringside observers believed Parker, thirty-one, merited the decision but the Derbyshire fighter experienced the second loss of his 28-bout career.
Buatsi Earns Triumph in Dull Encounter
Buatsi's progress has stalled in recent years through promotional disputes and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now stands trying to achieve expectations - possibly in what seems like a final roll of the dice - under recent support.
He started carefully, with both competitors ready to be aggressive in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second bout at light heavyweight.
By the halfway stage, Parker had stayed in contention, making life awkward for the favorite, who worked behind a protective stance to barely take the better periods.
The crowd's patience wore thin because of constant clinching, with the challenger going down multiple occasions during grappling.
The underdog finished the stronger, but several stanzas were hard to judge. Although, former world champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor moves on, but with the likes of heavy hitter David Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Inspires Local Rivalry Contest
In the co-main event, Arthur defeated Rea by close verdict in a outstanding Manchester vs Manchester contest to win the European light heavyweight belt.
The venue became quiet for a extremely emotional homage ahead of the contest as a bell ceremony sounded in honor of local hero Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the final chime disappeared, the quiet gave way to a shout of "only one Hatton".
The fighting within the ring equaled the emotion. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the initial stage, getting up unsteadily to his footing on the eight count.
But the traditional red attire of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was marked up quickly, significant bruising forming under his face as the fighters exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity hardly diminished over twelve rounds.
The victor barely secured the verdict with judges scorecards of even score, close margin and wider gap, but both fighters were persistent and full of heart, exactly what their inspiration the legend embodied.
